In current hydraulic systems, volumetric changes are common resulting from moving parts in the system and temperature changes in the hydraulic fluid. To account for these volumetric changes, current hydraulic systems include a reservoir tank to contain the overflow that occurs as a result of changes in the volume of the fluid. In any hydraulic system, it is important to prevent the ingestion of air into the system. In hydraulic reservoirs that are stationary, it is customary to ensure that the hydraulic fluid inlet is positioned at the top of the reservoir tank and exit from the bottom of the tank. Because the reservoir tank does not move, as long as the fluid outlet port is covered by hydraulic fluid, there is little risk of exposing the outlet port to the atmosphere. In non-stationary applications or in limited space applications, the reservoir tank may not always be in a position allowing gravity to ensure that the outlet port of the reservoir tank is covered by hydraulic fluid. Current approaches that address this issue involve additional structures and processes in an effort to allow the reservoir tank to tolerate movement. These approaches include pressurized systems and bladder-type systems. Pressurized systems may require specialized tools and equipment to depressurize and re-pressurize the system during repair and maintenance resulting in increased cost, duration, and complexity.